It is known to provide a fuel tank in a vehicle to hold fuel to be used by an engine of the vehicle. It is also known to provide a fuel pump inside the fuel tank to pump fuel to the engine. Typically, the fuel pump includes a check valve to allow fuel to exit the fuel pump. Generally, a forward flow check valve consists of a checking device, typically a plunger, such as a pintel having a seal, and a seat that when in contact form a leak proof seal. The pintel and seal are forced against the seat with a spring that provides the proper force to maintain pintel and seal to seat contact during no flow and low-pressure forward flow conditions. In automotive fuel pump applications, this force prevents flow from exiting the fuel tank when the vehicle fuel line is removed or severed.
Forward flow check valves having a pintel and seal can exhibit difficulties during low pintel travel conditions. During these conditions, a small flow area between the seal and seat creates a high velocity flow stream that creates a low-pressure venturi area, forcing the seal towards the seat. This venturi effect creates a high restriction by preventing the pintel from traveling and increasing the flow area. In addition, these check valves can exhibit oscillation if the annular area between the seal and the seat changes suddenly.
Therefore, it is desirable to provide a check valve in a fuel pump for a vehicle that eliminates a high restriction during low pintel travel conditions. It is also desirable to provide a check valve for a fuel pump that eliminates oscillation of the pintel. It is further desirable to provide a check valve for a fuel pump at a relatively low cost. Therefore, there is a need in the art for a check valve that meets these desires.